1. Field of the Invention
The present invention generally relates to a semiconductor device and a mold for manufacturing the same and, more particularly, is directed to a semiconductor device having a hollow package structure or the like, such as a CCD (charge-coupled device) area sensor integrated circuit, a CCD linear sensor integrated circuit, and so on, and a mold for manufacturing such a device.
2. Description of the Prior Art
Conventionally, in a semiconductor device having a solid-state image pickup device, such as a CCD linear sensor, a CCD area sensor or the like, a light transmissive member has been disposed so as to be opposite to an element formation surface (hereinafter simply referred to as "surface") of a semiconductor chip in order not only to protect the surface of the semiconductor chip but also to make light incident thereon. Plate glass is generally employed as such a light transmissive member.
FIG. 1 shows the sectional configuration of a conventional semiconductor device having a hollow package structure.
In the semiconductor device of FIG. 1, an inner lead of each lead frame 3 is wire-bonded with a wire 28 to a semiconductor chip 2 which is die-bonded onto a ceramic pedestal 1. A so-called window frame 4, which is a rectangular ring-like thin plate made of ceramic, is disposed and fixed to cover the surrounding of the inner leads. A rectangular transparent glass (hereinafter referred to as "cover glass" in accordance with connection) 5 is disposed and fixed onto the upper surface of the window frame 4. In this case, low melting-point glass 51 is used for providing a fixed connection between the pedestal 1 and the lead frames 3 and between the lead frames 3 and the window frame 4, and a thermosetting epoxy B-stage adhesive agent 6 is used for providing a fixed connection between the window frame 4 and the cover glass 5.
FIG. 2 shows the partially omitted sectional configuration of another conventional semiconductor device having a hollow package structure. In FIG. 2, parts the same as those in FIG. 1 are referenced correspondingly.
The semiconductor device of FIG. 2 has a tape 10 of a TAB (Tape Automated Bonding) system (hereinafter simply referred to as "TAB tape" in accordance with connection). This TAB tape 10 has, as well known, a four-layer structure of a polyimide base film 11, an adhesive agent 12, an inner lead 13 and a solder resist 14.
A wire is cut in a neck portion of a gold ball to form a gold bump on an aluminum (hereinafter abbreviated to "Al") pad on the surface of the semiconductor chip 2. This gold bump and the inner lead 13 of the TAB tape 10 are connected by gold-to-gold bonding (so-called single point bonding). Thereafter, the cover glass 5 is bonded to the base film 11 with a low-temperature-setting B-stage adhesive agent 7. The back of the semiconductor chip 2 is also sealed with resin 15.
A camera-incorporated VTR or the like, uses such a semiconductor device having a hollow package structure, in order to realize high performance operation, to reduce the size, weight and cost, and to improve the mechanical strength and accuracy.
To this end, recently, in the field of semiconductor device having a hollow package structure, investigation has been made as to possible production of the cover glass 5 with plastics (so-called transparent plastic lid which will be referred hereinafter to as "plastic lid") in order to attain improvement in optical characteristics, reduction in weight and in cost, and so on by improvement in the accuracy of attachment to a semiconductor chip.
However, with respect to the semiconductor device shown in FIG. 1, as a practical plastic material satisfying optical specification, there is no suitable adhesive agent other than amorphous polyolefine resin which has no polar radical. Therefore, it is necessary to perform surface treatment such as corona discharge treatment or the like upon a plastic lid made by such a material. As a result, production costs cannot be reduced. In addition, even if such bonding can be attained, there is one-digit difference in thermal expansion coefficient between the plastic lid and the ceramic pedestal 1. Therefore, there problems such as separation, and deterioration of air-tightness, and so on in temperature cycles occur, so that the development of practical plastic lids has not been possible.
Although bonding performed by an ultra-violet-ray (hereinafter abbreviated to "UV") radiation setting or a visible-ray radiation setting adhesive agent has been considered without using a thermosetting adhesive agent, these adhesive agents are generally in a liquid phase (A-stage). Therefore, gas released at the time of UV or visible light curing and at the time of after-baking adheres to the inside of a plastic lid in the hollow portion or an effective pixel region of the surface of a semiconductor chip such as a CCD area sensor or the like. Accordingly there has been a unevenness of sensitivity and deterioration of quality. Further, potential shift, discoloration of color filters and so on caused by charge-up of the semiconductor chip 2 at the time of UV radiation may occur.
On the other hand, in the semiconductor device shown in the example of FIG. 2, when the semiconductor chip 2 is sealed with the resin 15, it is possible that the semiconductor chip 2 may move while being sealed with the resin 15, in the case where the semiconductor chip 2 is, for example, a solid-state image pickup device such as a CCD linear sensor, a CCD area sensor or the like, because the number of the inner leads 13 connected to the semiconductor chip 2 is about 14. If the semiconductor chip 2 is moved, the surface of the semiconductor chip 2 is no longer parallel with the cover glass 5, so that the optical focus is no longer sharp which make the quality deteriorate or alternatively the inner leads may break off.
Moreover, in each of the semiconductor devices of FIGS. 1 and 2, .alpha. rays generated from impurities contained in the cover glass 5 acting as a lid are radiated onto the surface of the semiconductor chip 2, so that a dark current is produced in a solid-state image pickup device such as a CCD linear sensor, a CCD area sensor or the like due to so-called damage by the .alpha. rays. Particularly in the semiconductor device of FIG. 2, since the resin 15 exists on and above the surface of the semiconductor chip 2, a dark current is produced by .alpha. rays generated from glass beads mixed as filler in the resin 15.